Reforming catalyst



REF QRMING CATALYST Armand J. de Rosset, Clarendon Hills, and VladimirHaeusel, Hinsdale, lll., assigno-rs to Universal Oil Products Company,Des Plaines, lll., a corporation of Delaware No Drawing. ApplicationJuly 17, 1953 Serial No. 368,826

8 Claims. (Cl. 252-442) This invention relates to a reforming processand to the manufacture of catalysts for use therein.

The term reforming is well known in the petroleum industry and refers tothe treatment of gasoline fractions to improve the antiknockcharacteristics thereof. The petroleum fraction that is upgraded inreforming may be a full boiling range straight run gasoline having aninitial boiling point within the range of from about 50 F. to about 100F. and an end boiling point within the range of from about 350 F. toabout 425 F. It may also be a natural gasoline as obtained from therefining ofnatural gases or it may be any selected fraction of thenatural gasoline. The natural gasoline or the natural gasoline fractionwill have an initial boiling point and an end boiling pointsubstantially the same as that of the gasoline hereinbefore described.In the reforming process the gasoline fraction that is selected usuallyis the higher boiling fraction, commonly referred to as naphtha, andgenerally will have an initial boiling point of from about 150 F. toabout 250 F. and an end boiling point within the range of from about 350F. to about 425 F. The catalyst of the present invention may also beapplied to the reforming of cracked gasoline ormixtures of cracked andstraight run and/ or natural gasoline. Reference to gasoline in thepresent specification, therefore, means a full boiling range gasoline orany fraction thereof, and also that the gasoline fraction may containcomponents boiling above the gasoline range.

, In the reforming process there are four major reactions. The first isan aromatization reaction in which naphthene hydrocarbons are convertedto aromatics. The second is a dehydrocyclization reaction in which thestraight chain or slightly branched chain paraffins are cyclicized toform aromatics. Third is an isomerization reaction in which straightchain or slightly branched chain parafiins are converted to morebranched chain parafiins. This reaction occurs as a result of a strainput upon a carbon to carbon bond so that there is a shift of a carbonatom in the molecule to form a more branched chain molecule. In thisspecific reaction there is no change of molecular weight The reactionmay also be characterized as increasing the number of methyl groups inthe hydrocarbon molecule. The fourth is a cracking reaction in which theheavier straight chain or slightly branched chain paraffins, which havelow antiknock characteristics, are converted to lighter straight chainor branched chain paratfins which have higher antiknock characteristics.When this last reaction is conducted in the presence of hydrogen, theunsaturated hydrocarbon that is formed as a result of the crackingoperation, is saturated to the paraffin by reaction with hydrogen in thepresence of the reforming catalyst. The cracking or splitting of thecarbon to carbon bond is one of the more important reactions in asuccessful reforming process. It is necessary that the splitting of thecarbon to carbon bond be controlled so that there is no excessiveformation of normally gaseous products. For example, it would bepossible to crack a C hydrocarbon to form ten molecules of methane,however, unless methane is the specifically desired product, it would beuneconomical in a reforming process to crack the C hydrocarbon to formmethane. It is more desirable to crack a-C hydrocarbon so that twomolecules of pentane are formed and it would be still more desirable if,during the reaction,

isomerization would simultaneously take place so. that the productobtained would be isopentane. It is an ob.- ject of the presentinvention to provide a catalyst wherein the cracking activity iscontrolled and selective so that excessive amounts of normally gaseousproductsare not produced in a reforming process.

Uncontrolled or non-selective cracking results in the more rapidformation of larger quantities of coke ,or carbonaceous matter whichdeposits on the catalyst and decreases or destroys its activity tocatalyze the desired reactions. This in turn results in shorterprocessing cycles or periods with the necessity of more frequentregeneration of the catalyst by burning the carbonaceous productstherefrom, or should the catalyst activity be destroyed it will benecessary to shut down the unit to remove the old catalyst and replaceit with new catalyst. Another important feature in a successful]reforming process is the matter of hydrogen production and consumption.of hydrogen in the reforming zone further tends to decrease the amountof carbonaceous deposit on the catalyst. In view of the fact that thecost of hydrogen is quite high, it is essential that there be no netconsumption of.

hydrogen or, in other words, at least asmuch hydrogen must be producedin the process as is consumed therein.

While the catalyst of the present invention is particu larly suitablefor the reforming of gasoline, it is understood that this novel catalystmay be utilized for the conversion,

of other hydrocarbon fractions. Thus the catalyst may be used for thedehydrogenation of selected hydrocarbon,

fractions such as naphthenes to produce aromatics in- Investigation hasshown that the presence.

eluding, specifically, the dehydrogenation of cyclohexane to benzene,methylcyclohexane to toluene, ethylcyclohexane to ethylbenzene, etc.,the dehydrogenation of parafifins to produce the corresponding olefins,including, specifically, dehydrogenation of butane to butene, pentane topentene, hexane to hexene, etc., the dehydro genation mono-olefins toproduce the corresponding diolefins including, specifically,dehydrogenation of butene.

to butadiene, pentene to pentadiene, etc. The catalyst may also beutilized to effect dehydrocyclization reactions including, specifically,the conversion of normal hexane to benzene, normal heptane to toluene,etc. The

catalyst may also be used for effecting isomerization reactionsincluding the isomerization of normal or mildly branched chainparafiins, the isomerization of alkyl cyclic compounds to isomersthereof, including the isomeriza tion of methylcyclopentane tocyclohexane, ethylcyclo pentane to methylcyclohexane, etc., theisomerization of alkyl benzenes, etc.

Furthermore, the catalysLmay be used for effecting hydrogenationreactions including nondestructive hydrogenation, as for example, the:hydro-. genation of butene to butane, pentene to pentane, aromat ics tocycloparaffins, etc., and destructive hydrogenation of heavier oil togases and/or gasoline fractions. In

still another embodiment the catalyst of the present in- In the desul-das mercaptans or thiophenes are converted to hydrogen,

sulfide which may be stripped out in subsequent opera! tions.

amma 3 In one embodiment the present invention relates to a method ofpreparing a catalyst which comprises commingling alumina with a solutionof a platinum compound containing a water soluble acidic compound notsubstantially reactive with the alumina at impregnating conditions, andwith a solution of hydrogen fluoride containing a water soluble acidiccompound not substantially reactive with the alumina at impregnatingconditions, said platinum compound being in an amount to form a finalcatalyst containing from about 0.01% to about 1% by weight of platinum,and said hydrogen fluoride being in an amount to form a final catalystcontaining from about 0.1% to about 8% by weight of combined fluorine.

In another embodiment the present invention relates to a method ofpreparing a catalyst which comprises commingling with, alumina asolution of a platinum compound, hydrogen fluoride and a water solubleacidic compound not substantially reactive with the alumina atimpregnating conditions, said platinum compound being in an amount toform a final catalyst containing from about 0.01% to about 1% by weightof platinum, and said hydrogen fluoride being in an amount to form afinal catalyst containing from about 0.1% to about 8% by weightof'combined fluorine.

In a specific embodiment the present invention relates to a method ofpreparing a catalyst which comprises commingling with dry precipitatedalumina particles of definite size and shape, a solution containingchloroplat-inic acid, hydrogen fluoride and a sufficient amount of awater soluble acidic compound not substantially reactive with thealumina at impregnating conditions to lower the pH, said chloroplatinicacid being in an amount to form a final catalyst containing from about0.01% to about 1% by weight of platinum, and said hydrogen fluoridebeing in an amount to form a final catalyst containing from about 0.1%to about 8% by'weight of combined fluorine, and calcining the thustreated alumina particles.

In a further embodiment the present invention relates to a process forreforming a gasoline fraction which comprises subjecting said fractionto contact at reforming conditions with a catalyst prepared bycomrningling with alumina a solution of a platinum compound, hydrogenfluoride and a water soluble acidic compound not substantially reactivewith the alumina at impregnating conditions to lower the pH, saidplatinum compound being in an amount to form a final catalyst containingfrom about 0.01% to about 1% by weight of platinum, and said hydrogenfluoride being in an amount to form a final catalyst containing fromabout 0.1% to about 8% by weight of combined fluorine, and calcining.

Platinum-containing catalysts and various methods of manufacture haveheretofore been suggested. These catalysts have been of limitedcommercial acceptance because of the high cost thereof. It has beenfound that exceptionally good platinum-containing catalysts are preparedin accordance with the novel features of the present invention. Whilethese catalysts may contain larger concentrations of platinum which mayrange up to about 10% by weight or more of the alumina, it has beenfound that exceptionally good catalysts may be prepared to contain fromas low as about 0.01% to about 1% by weight of platinum. Catalysts ofthese low platinum concentrations are particularly preferred in thepresent invention because of the considerably lower cost of the catalystand thus enhances the attractiveness of the catalyst for use incommercial processes.

' However, in order to obtain improved results with these low platinumconcentrations, it is necessary that a particulaf'jtype of supportingcomponent be composited with the platinum, especially when the supportcontains halogen inspeciflc'amounts. It has been found that aluminashows unexpected advantages for use as a supporting component for thelow platinum concentration and low halogen concentration, apparently dueto some peculiar association of the alumina with the platinum and withthe halogen either as a chemical combination or as a physicalassociation. Platinum-halogen on other supports such as alumina-silica,alumina-titania, alumina-magnesia and alumina-boron oxide also showscatalytic activity and the method of our invention for compositingplatinum and halogen with the alumina may also be used for compositingplatinum and halogen with these other alumina-containing components, butnot necessarily with equivalent results. When the halogen is combinedwith the combination such as alumina-silica, the halogen reacts withboth the alumina and the silica, however, the silica-halogen compoundmay vaporize from the catalyst and thus the catalyst will not contain asilica-halogen compound such as, specifically, silicon, tctrafluoride,but will contain the aluminum halide.

As another essential feature of the present invention impregnation ofthe alumina must be effected in the presence of an acidic compound whichmay be an inorganic acid, an organic acid and/or an acid acting salt. Aparticularly suitable method of impregnation is by means of a solutionof a suitable platinum compound. However, it has been found that unlessthe impregnation is effected in the presence of an acidic compounduneven distribution of the platinum and the fluorine in or on thealumina particles is obtained. Usually this uneven distributioncomprises surface coating, that is, the platinum compound and fluorineare distributed on only the surface of the particles and not evenlythroughout the mass. By effecting the impregnation in the presence of anacidic solution, even distribution of the platinum and fluorinethroughout the alumina particles is obtained. Catalysts containing anon-uniform distribution of the platinum and fluorine are notsatisfactory apparently due to a peculiar association of the platinumand halogen and alumina which is required to produce satisfactorycatalysts. It appears that a particular spacial arrangement of theplatinum in relation to the alumina and to each other is necessary inorder to obtain satisfactory catalysts.

The desired arrangement is not achieved when the platinum atoms aregrouped too closely to the others or are spaced at too great a distanceapart. In any event, the

use of an acid along with chloroplatinic acid and hydro gen fluorideresults in a solution which is used for compositing with the alumina inaccordance with this invention.

Heretofore it has been suggested that a basic compound be added to theplatinum-containing solution prior to compositing with the support.Specifically, ammonium hydroxide was added to a solution ofchloroplatinic acid and the theory set forth was that the ammoniaassociated itself with the chloroplatinic acid forming a complex whichin turn homogeneously distributed itself instead of associating itselfwith the surface of the alumina particles thoroughly impregnates thealumina particles to produce a final catalyst in which the platinum isuniformly distributed throughout the alumina. This explanation is alsoapplicable to the beneficial effect noted when impregnating the aluminawith the fluoride. Hydrogen fluoride is a weak acid in comparison toacids such as hydrochloric and nitric and, therefore, when an acid suchas nitric acid is added to a solution of hydrofluoric acid, theionization of hydrofluoric acid to the hydrogen ion and the fluoride ionis suppressed. Therefore, by the presence of an acid, the hydrogenfluoride is rendered more inactive, that is, it is present more as themolecule HF and the hydrogen fluoride will more thoroughly im-- pfegnatethe alumina particles before reacting with the alumina.

'Ihe acidic compound that is selected must be one that is notsubstantially reactive with the alumina at impregnating conditions, andpreferably is one that is not substantially reactive with the alumina atany of the conditions in which it is in contact with the alumina duringthe preparation of the catalyst. In some cases only certainconcentrations of the acidic compound are substantially reactive withthe alumina and these concentrations should not be used. An acidiccompound may be used, however, when it is reactive with the alumina, ifthe resultant product or residue is not harmful to the catalyst and/orif the resultant product or residue is removed in a further treatment,such as washing or calcination, and/ or if the formation of theresultant product or residue does not harm the final catalyst. It ispreferred, however, that the acidic compound be water soluble andsubstantially unreactive with the alumina. In most cases it may beremoved by washing or by calcination. Most concentrations of aqueoussolutions of hydrogen halides and specifically hydrogen fluoride and/ orhydrogen chloride are reactive with the alumina and therefore they arenot to be used as the acidic compound of our invention.

Likewise higher concentrations of sulfuric acid, especially at elevatedtemperature are reactive with the alumina and these higherconcentrations and elevated temperatures are not to be used whenemploying sulfuric acid. Usually the impregnation is done at aconcentration and temperature such that the sulfuric acid is notreactive with the alumina and at these concentrations and temperaturesit may be used.

A particularly satisfactory method of impregnatingthe alumina with theplatinum comprises the use of an aqueous solution of chloroplatinic acidcontaining a water soluble acidic compound not substantially reactivewith the alumina at impregnating conditions. In one embodiment theacidic compound is added to chloroplatinic acid and the mixture is addedto the alumina particles. Subsequently an acidic compound notsubstantially reactive with the alumina at impregnating conditions, isadded to an aqueous solution of hydrogen fluoride and the mixture isadded to the alumina particles. The reverse procedure may also be used,that is, the alumina may first be impregnated with the fluoride-acidiccompound containing solution and subsequently impregnated with theplatinum-acidic compound containing solution. In still anotherembodiment the alumina may be calcinedbefore impregnating with any oneor with both of the solutions and also the alumina after comminglingwith the halogen-containing solution may be calcined before comminglingwith the platinum-containing solution, and likewise the alumina aftercommingling with the platinumcontaining solution may be calcined beforecontacting with the halogen-containing solution. In any event, themixture is allowed to stand, preferably with or after suitable agitationso that thorough mixing is obtained and even distribution of theplatinum and halogen throughout the alumina particles is effected. Theinvention therefore, is directed to the use of an acidic compound notsubstantially reactive with the alumina at commingling conditions. Whencommingling alumina with a platimum-containing compound and hydrogenfluoride, the alumina may be commingled with a solution containing boththe platinum-containing compound and hydrogen fluoride in the presenceof the acidic compound, or else the alumina may be impregnated with theplatinum-containing solution first, followed by impregnating with thefluoride-containing solution, or, as hereinabove set forth, the reverseprocedure may be used.

1 The solution of platinum-compound and acidic compound may be preparedin any suitable manner. Chloroplatinic acid is the preferred platinumcompound to be used in accordance with the present invention because ofits ready availability and lower cost. It is understood that otherplatinum compounds may be used in accordance with the present invention,however, not necessarily with equivalent results. As hereinbefore setforth, the amount of platinum compound utilized is preferably controlledso that the final catalyst contains from about 0.01% to about 1% byweight of platinum.

A solution of platinum compound, hydrogen fluoride and acidic compoundmay also be prepared in any suitable manner. The order of mixing ofthese compounds is usually not important in that there does not appearto be any substantial chemical reaction involved when mixing thesecompounds, other than the usual. ionization, that is, no new gaseouscompound is evolved during the mixing, or no precipitate forms duringthe mixing.

Any suitable acidic compound may be used within the scope of the presentinvention. When preparing the solution of the platinum compound andacidic compound, the preferred acidic compounds comprise the acids,nitric acid, sulfuric acid, phosphoric acid and aluminum nitrate. Othersuitable acids include acetic acid, oxalic acid, formic acid, propionicacid and more generally include acids and acid salts which are moreacidic than chloroplatinic acid or any other platinum-containingcompound that is selected. Mixtures of acidic compounds may also be usedwithin the scope of this invention. As hereinbe fore set forth theacidic compound must not be substantially reactive with the alumina atconcentrations or at temperatures as herein set forth. When preparingthe solution of platinum compound, hydrogen fluoride and acidic compoundor the solution of hydrogen fluoride, and acidic compound, the preferredacidic compounds usually comprise the stronger acids since it isbelieved that one of the beneficial effects of an acidic compound it tosuppress the ionization of hydrogen fluoride to render it more inactivewith the alumina and, therefore, the acidic compound must be chosen withthe view to suppressing the ionization of hydrogen fluoride. Thepreferred acidic compounds therefore to use when hydrogen fluoride ispresent comprise the acids, nitric acid, sulfuric acid, and phosphoricacid. While the organic acids which include acetic acid, oxalic acid,formic acid, and propionic acid may be used, they are not as suitablesince they do not as actively suppress the ionization of hydrogenfiuoride as the aforementioned acids. Mixtures of acidic compounds mayalso be used in the hydrogen fluoride containing impregnating solution.

The amount of acidic compound required will vary with the particularacidic compound and with the particular solution utilized. In generalonly a small amount of acidic compound will be required and usually willbe in amount sufficient to lower the pH of the platinumcontainingsolution to below 2.5 and preferably below 2.0. When the impregnatingsolution contains hydrogen fluoride the amount of acidic compound willmore usually be in amount sufficient to lower the pH of the solution tobelow about 1.0.

The amount of acidic compound that is to be added may be measured by theamount necessary to lower the impregnating solution to a specified pH.The preferred method is by measuring a stoichiometric amount of acidiccompound that is added to the platinum-containing solution and/or to thehalogen-containing solution and/or to the platinum andhalogen-containing solution. The pH of the solution containing thehydrogen fluoride does not change much upon the addition of a smallamount of acidic compound since the hydrogen fluoride acts as a weakacid and the ions of hydrogen and fluorine combine to form the hydrogenfluoride molecule. The same effect is noticed when adding small amountsof acid to chloroplatinic acid solutions. The concentration of acidiccompound will be within the range of from about 0.001 to about 5.0 molarwith respect to said acidic compound and preferably from about 0.005 toabout 3.0 molar. Concentrations below this'wider range are too weak tobe 7 e'fiective and concentrations above this range often are tooreactive with the alumina.

The alumina for use in the present invention may be prepared in anysuitable manner. A particularly preferred method is to prepare aluminaby adding a suitable reagent, such as ammonium hydroxide, ammoniumcarbonate, etc., to a salt of aluminum such as aluminum chloride,aluminum nitrate, aluminum acetate, etc., in an amount to form alumiumhydroxide which, upon drying is converted to alumina and in the interestof simplicity, the aluminum hydroxide is referred to as alumina in thepresent specification and claims in order that the percentages are basedon the alumina free of combined water. It has been found aluminumchloride is generally preferred as the aluminum salt, not only forconvenience in subsequent washing and filtering procedures, but alsobecause it appears to give best results.

After the alumina has been formed it is generally washed to removesoluble impurities. Usual washing procedures comprise washing withwater, either in combination with filtration or as separate steps. Ithas been found that filtration of the alumina is improved when thewash-water includes a small amount of ammonium hydroxide. The severityof washing will depend upon the particular method employed in preparingthe catalyst. In one embodiment of the invention the alumina isthoroughly washed with a suitable amount of water and preferably watercontaining ammonium hydroxide to reduce the chlorine content of thealumina to below about 0.1%. In another embodiment of the invention thiswashing may be selective to retain chloride ions in an amount of fromabout 0.2% to about 8% by weight of the alumina on a dry basis. Ingeneral, it is preferred to wash the alumina thoroughly and if it isdesired to add chlorine it is added as a separate step because bettercontrol of the amount of chlorine is obtained in this manner.

In some cases it is desirable to prepare the catalyst in the form ofpills of uniform size and shape and this may readily be accomplished bygrinding the partially dried alumina cake with a suitable lubricant suchas stearic acid, rosin, graphite, etc. and then forming the pills in anysuitable pelleting or extrusion apparatus. The halogen may be addedbefore or after forming the alumina into particles of uniform size andshape. In still another embodiment the halogen and platinum addition maybe effected prior to forming the composite into particles of uniformsize and shape.

Alumina spheres may be continuously prepared by passing droplets of analumina sol into an oil bath maintained at an elevated temperature andretaining the droplets in said oil bath until the droplets set to gelspheres. The spheres are continuously withdrawn from the oil. bath andimmediately thereafter aged prior to being contacted with water oraqueous solutions. may then be dried and calcined at a temperature offrom about 500 F. to 1400 F. or more.

As hereinbefore set forth the platinum and the halogen may be compositedwith the alumina in three ways. In one method the alumina is impregnatedwith a solution of a platinum compound containing the acidic compound.In the second method the alumina is impregnated with a solution ofhydrogen fluoride containing an acidic com pound. In the third methodthe alumina is impregnated with a solution of platinum compound,hydrogen fluoride and the acidic compound.

The solution of platinum and acidic compound may be composited with thealumina in any suitable manner. When the solution is to be compositedwith the alumina in a wet condition, this is readily accomplished byadding the solution to the alumina and thoroughly mixing the same toobtain uniform distribution after which the composite is washed and thewashed material is dried at a temperature of from about 200 F. to about500 F. for a period of from about 2 to 24 hours or more. It is also Thespheres possible to add the acidic compound to the alumina prior to theaddition of the solution of the platinum compound, however, theplatinum-containing compound and the acidic compound are more usuallymixed before compositing with the alumina. When particles of irregularsize and shape are desired, the dried material may be ground and thencalcined at a temperature of from about 700 F. to about 1100 F. for aperiod of from about 2 to 12 hours or more. On the other hand, whenparticles of uniform size and shape are desired a suitable lubricant,such as stearic acid, rosin, hydrogenated coconut oil, graphite, etc.are added to the dried material and then it is formed into particles ofuniform size and shape by any suitable method such as pelleting,extrusion, etc. T he particles are then calcined at a temperature withinthe range as hereinbefore set forth. The manner of compositing thesolution of platinum compound and acidic compound with the alumina, ashereinabove set forth, is also used when the alumina is previouslycomposited with the fluorine.

The solution of hydrogen fluoride and acidic compound may be compositedwith the alumina in any suitable manner. The hydrogen fluoride is a formwhich will readily react with the alumina and the presence of the acidiccompound not substantially reactive with the alu mina at comminglingconditions, produces an aluminafluoride composite in which the fluorineis more uniformly distributed than when the acidic compound is absent.An aqueous solution of hydrogen fluoride can be easily handled and byits use the specific amount of fluoride to be added may be easilycontrolled.

The concentration of hydrogen fluoride in the finished catalyst will bewithin the range of from about 0.1% to about 8%. The fluoride ionhowever, appears to be very active when reforming certain gasolinefractions and the higher concentrations are not as desirable andtherefore the preferred range of fluoride concentration is from about0.1% to about 3% by weight of the alumina on a dry basis. Concentrationsof fluorine above 3% sometimes adversely effect the selectivity of thecatalyst, thus catalyzing side reactions to an extent greater thandesired.

The solution of platinum compound, hydrogen fluoride and acidic compoundmay be composited with the alumina in'substantially the same manner ashereinabove set forth. The amount of hydrogen fluoride present will becontrolled so that the amount of fluoride present on the final catalystwill fall within the range of from about- 0.1% to about 8% by weight ofthe final catalyst, and likewise the amount of platinum compound will becontrolled so that the amount of platinum on the final catalyst will bewithin the range of from about 0.01% to about 1% by weight. When thissolution is used the amount of acidic compound present is that amountwherein the concentration of the acidic compound in the impregnatingsolution lies within the range of from about 0.001 to about 5.0 molarwith respect to said acidic compound.

In a preferred embodiment of the invention the alu mina prior tocommingling with the other components is formed into particles ofdefinite size and shape. This is accomplished in substantially the samemanner as hereinbefore set forth, but before the platinum is compositedwith the alumina, the alumina particles may be calcined at a somewhathigher temperature which may range from about 500 F. to about 1400 F.Commingling of any of the hereinbefore mentioned solutions may beaccomplished in any suitable manner including soaking the alumina pillsin the solution and either drainingoff the excess solution or heating toremove the volatizible materials. Another suitable method is by dippingthe alumina particles in the solution. In any event the alumina iscontacted with the solution for a suflicient period of time to obtainuniform distribution of the solution throughout the alumina after whichthe composite may be dried at a temperature of from about 200 F. to

gamma about 500 F. for a period from-about 2 to. 24 hours or more andthen calcined at atemperature of from about 700 F. to about 1100 F. fora period of from about 2 to 12 hours or more. The upper temperaturelimit of 1100 F. is necessary when the alumina is already cor npositedwith the platinum, however, when the composite is alumina-halogen oralumina itself, the calcination may be performed in a temperature rangeof from about 500 F. to about 1400 F. for a period of from about 2 to 24hours or more. In another embodiment the alumina is combined with ahalogen and the alumina'halogen com posite may be treated as hereinaboveset forth. The calcination is preferably effected in the presence of airor other oxygen-containing gas. In another embodiment of the inventionthe calcination may comprise a two-stage method in which it is firstcalcined in the presence of hydrogen followed by calcination in air orthe reverse procedure may be used.

In some cases the lubricant may be removed during the high temperatureheating. In other cases, as for example, when graphite is used as thelubricant the separate high temperature heating step may be omitted andthe effective heat treatment of the catalyst may be obtained in theplant before or during processing of the hydrocarbon.

Although the catalyst of the present invention will have a long life, itmay be necessary to regenerate the catalyst after long periods ofservice. The regeneration may be efiected by treatment with air or otheroxygencontaining gas to burn carbonaceous deposits therefrom. Generallyit is preferred to control the regeneration temperature not to exceed1000 F. and preferably the re generation is effected at a temperaturewithin the range of from about 600 F. to about 900 F.

The exact operating conditions used when employing the catalyst of thisinvention will depend upon the character of the charging stock as wellas the activity of the catalyst being used, however, the conditionsusually will be in the following ranges: Temperatures fromabout 500 F.to about 1000 F., a pressure of from about 50 to about 1000 p. s. i. ormore, a weight hourly space velocity (defined as the weight of oil perhour per weight of catalyst in the reaction zone) of from about 0.5 toabout 20 or more. The reforming is preferably effected in the presenceof hydrogen which may be introduced from an extraneous source orrecycled within the process. In one embodiment of the process sufficienthydrogen will be produced in the reforming reaction to furnish thehydrogen required in the process and, therefore, it may be unnecessaryto either introduce hydrogen from an extraneous source or to recyclehydrogen within the process. However, it usually will be preferred tointroduce hydrogen from an extraneous source at the beginning of theoperation and to recycle hydrogen within the process in order to beassured of a suflicient hydrogen atmosphere in the reaction zone. Thehydrogen present in the reaction zone will be within the range of fromabout 0.5 to about 20 mols of hydrogen per mol of hydrocarbon. In somecases the gas to be recycled will contain hydrogen sulfide introducedwith the charge or liberated during the reaction and it is within thescope of the present invention to treat the hydrogen-containing gas toremove hydrogen sulfide or other impurities before recycling thehydrogen within the process.

Other selected processing conditions are required depending upon theparticular reaction desired. For example, for dehydrogenation of normalbutane the temperature should be within the range of from about 800 F.to about 1100 F., the pressure from about atmospheric to about 50 lbs.per sq. inch, and the gaseous hourly space velocity from about 200 toabout 5000. For hydrogenation reactions the temperature may range fromatmospheric to about 500 F., the pressure from about 100 to about 3000lbs. per sq. inch or more and the weight hourly space velocity fromabout 0.5 to 5.

Processes using the catalyst of the present invention.

may be effected in any suitable equipment. The finished catalyst may bedeposited as a fixed bed in a reactor and the hydrocarbons to be treatedare passed therethrough in either upward or downward flow. The catalystmay be used in a fluidized type of operation in which the catalyst andhydrocarbons are maintained in a state of turbulence under hinderedsettling conditions, or a fluidized fixed bed type of operation may beused in which the catalyst and hydrocarbons are maintained in a state ofturbulence under hindered settling conditions but where catalyst is notwithdrawn from or introduced into the reaction zone during theprocessing cycle. The catalyst may also be used in the moving bed typeof process in which the catalyst and hydrocarbons are passed either inconcurrent or countercurrent flow through a reaction zone, and thecatalyst may also be used in the suspensoid type of operation in whichthe catalyst and hydrocarbons are passed as a slurry through thereaction zone. The reactants from any of the hereinbefore mentionedreaction zones are normally subjected to a further treatment, such asthe stabilization of the product to separate normally gaseous parafiinstherefrom to obtain a final reformed product of the desired volatilityand vapor pressure.

The following examples are given to further illustrate the novelty andutility of the present invention, but are not given for the purpose ofunduly limiting the generally broad scope of the present invention.

EXAMPLE I A catalyst was prepared by adding ammonium hydroxide toaluminum chloride hexahydrate to form aluminum hydrate. The resultantaluminum hydrate was washed thoroughly in order to reduce the chloridecontent to below 0.1% by weight on a dry basis. The alumina was dried ata temperature of about 340 F. for 8-10 hours and the partially driedalumina was ground, Stearotex added as a lubricant, and then pilled in aStokes pelleting machine to form cylindrical pills of 5;" x in size. Thepills were then calcined in air at a temperature of about 1232 F. for 3hours. The pills were then submerged in an aqueous solution containingchloroplatinic acid, hydrogen fluoride, and nitric acid. The nitric acidwas used in an amount so that the impregnating solution was 1.5 molar innitric acid. The solution was used in concentration and amount toproduce a final catalyst containing 0.49% platinum and 0.31% fluorine.This catalyst is referred to as catalyst A.

Another catalyst, referred to as catalyst B, was pre pared insubstantially the same manner as catalyst A, however, nitric acid wasomitted from the impregnating solution. After impregnation the mixtureswere evaporated to dryness and the pills subsequently calcined in air ata temperature of about 932 F. for approximately 3 hours.

Catalysts A and B were used for reforming a Mid- Continent naphthahaving an initial boiling point of 210 F. and an end boiling point of390 F. The conditions maintained in the reforming zone were an averagecatalyst temperature of 860 F., a pressure of 500 lbs. per sq. inch, aliquid hourly space velocity of about 2 and a hydrogen to hydrocarbonmol ratio of about 3.1. An analysis of the reformed products are shownin the following table.

The dispersion value is a measure of the aromatic content of thegasoline and it may easily be seen that u catalyst A, as preparedaccording to the method of our 11 invention, had superior aromatizingproperties. The octane number of the product produced by catalyst A isalso substantially higher than that produced using catalyst B.

EXAMPLE II Alumina pills are prepared as outlined in Example I. Thepills are then submerged in an aqueous solution containingchloroplatinic acid, hydrogen fluoride, and sulfuric acid. The sulfuricacid is used in an amount so that the solution is 0.50 molar withrespect to the sulfuric acid. The solution is in a concentration andamount to produce a final catalyst containing 0.3% platinum and 0.4%fluorine. This catalyst is referred to as catalyst C. Catalyst D isprepared in a similar manner except sulfuric acid is not used. Theplatinum and halogen of catalyst C will be more evenly distributed thanthe platinum and halogen of catalyst D. Catalyst C will also maintainits activity for a longer period of time than catalyst D when they areused in a reforming process.

EXAMPLE III A catalyst is prepared by calcining alumina pills at 1232 F.for approximately 3 hours. The alumina pills are submerged in a solutionof 4.8% hydrofluoric acid to which nitric acid is added in an amount tomake the solution 0.5 molar with respect to the nitric acid. Thesolution is prepared and used in an amount so that the final catalystwill contain 0.5% by weight of fluoride based on the alumina on a drybasis. The pills and solution are evaporated to dryness and are thensubmerged in a solution of chloroplatinic acid containing nitric acid inan amount to lower the pH of the solution to about 1.5. The solution andpills are again evaporated to dryness and calcined in air at atemperature of 932 F. for 3 hours.

An inspection of the final catalystshows that the halogen and theplatinum are distributed very evenly through the pills. This catalyst isreferred to as catalyst E.

Another catalyst is prepared in substantially the same manner exceptthat the nitric acid is left out of the chloroplatinic acid solution.This catalyst is referred to as catalyst F.

Catalysts E and F are treated with a stream of hydrogen sulfide toconvert the platinum into platinum sulfide which is a dark color. Aninspection of catalysts E and F shows that the platinum in catalyst E ismuch more evenly distributed through the catalyst mass. The platinum ofcatalyst F is found on the surface of the alumina pills with littlepenetration into the center of the pill.

The catalysts may be used for reforming a Mid-Corr tinent naphtha havingan initial boiling point of 190 F. and an end'bo-iling point of 390 F.Over an extended period of operation the activity of catalyst E willremain higher than the activity of catalyst F.

We claim as our invention:

1. In the manufacture of a catalyst comprising platinum, alumina andfluorine, the improvement which comprises impregnating alumina With asolution containing chloroplatinic acid, hydrogen fluoride and anadditional mineral acid selected from the group consisting of nitric,sulfuric and phosphoric acids, the concentration of said mineral acidand the impregnating temperature being such that there is no substantialreaction between the alumina and mineral acid during the impregnation,the hydrogen fluoride being in an amount to form a final catalystcontaining from about 0.1% to about 8% by weight of combined fluorineand said additional acid being in an amount to lower the pH of saidsolution to below 2.5.

2. The improvement as defined in claim 1 further characterized in thatthe amount of said mineral acid is suflicient to lower the pH of thesolution to below about 1.0.

3. The improvement as defined in claim 1 further characterized in thatsaid solution is from about 0.001 to about 5.0 molar with respect tosaid mineral acid.

4. The improvement as defined in claim 1 further characterized in thatsaid mineral acid is nitric acid.

5. The improvement as defined in claim 1 further characterized in thatsaid mineral acid is sulfuric acid.

6. The improvement as defined in claim 1 further characterized in thatsaid mineral acid is phosphoric acid.

7. In the manufacture of a catalyst comprising platinum, alumina andfluorine, the improvement which comprises impregnating alumina with asolution containing a platinum compound and hydrogen fluoride insuflicient amounts to form a final catalyst containing from about 0.01%to about 1% by weight of platinum and from about 0.1% to about 8% byweight of combined fluorine, said solution additionally containing atleast one acid selected from the group consisting of nitric, sulfuricand phosphoric acids in an amount to impart to the solution a pH valuebelow about 1.0.

8. In the manufacture of a catalyst comprising platinum, alumina andfluorine, the improvement which comprises impregnating alumina With asolution containing a platinum compound and hydrogen fluoride insufiicient amounts to form a final catalyst containing from about 0.01%to about 1% by weight of platinum and from about 0.1% to about 8% byweight of combined fluorine, said solution additionally containing atleast one acid selected-from the group consisting of nitric, sulfuric,phosphoric, acetic, oxalic, formic and propionic acids in an amount toimpart to the solution a pH value below about 1.0.

References Cited in the file of this patent UNITED STATES PATENTS2,331,915 Kirkpatrick Oct. 19, 1943 2,479,109 Haensel Aug. 16, 19492,611,736 Haensel Sept. 23, 1952 2,636,863 Haensel Apr. 28, 19532,753,310 Riedl July 3, 1956 2,769,688 Milliken et a1. Nov. 6, 1956

1. IN THE MANUFACTURE OF A CATALYST COMPRISING PLATINUM, ALUMINA ANDFLUORINE, THE IMPROVEMENT WHICH COMPRISES IMPREGNATING ALUMINA WITH ASOLUTION CONTAINING CHLOROPLATINIC ACID, HYDROGEN FLUORIDE AND ANADDITIONAL MINERAL ACID SELECTED FROM THE GROUP CONSISTING OF NITRIC,SULFURIC AND PHOSPHORIC ACIDS, THE CONCENTRATION OF SAID MINERAL ACIDAND THE IMPREGNATING TEMPERATURE BEING SUCH THAT THERE IS NO SUBSTANTIALREACTION BETWEEN THE ALUMINA AND MINERAL ACID DURING THE IMPREGNATION,THE HYDROGEN FLUORIDE BEING IN AN AMOUNT TO FORM A FINAL CATALYSTCONTAINING FROM ABOUT 0.1% TO ABOUT 8% BY WEIGHT OF COMBINED FLUORINEAND SAID ADDITIONAL ACID BEING IN AN AMOUNT TO LOWER THE PH OF SAIDSOLUTION TO BELOW 2.5.